Liquid applicator



F. S. BARTLETT LIQUID AP'PLICATOR July 18, 1944.

Filed June a, 1941 2 Sheets-Sheet 1 INVENTORL m r M a m m m i f if Q Y EN R. 0 T T A y 1944. F. s. BARTLETT ,9

LIQUID APPLI CATOR Filed June 6, 1941 2 Sheets-Sheet 2 A TTORNEYPatented July 18, 1944 LIQUID APPLICATQR Frederick S. Bartlett, Bristol,R. L, asslgnor to United. States Rubber Company, New York, N. Y., acorporation of New Jersey Application June s, 1941, Serial No. 396,790

1 Claim. (01. 9l-50) This invention relates to the application ofliquids to elongated articles such as wire, and is of particular utilitywhen employed for applying liquid dispersions or solutions of insulatingmaterials to conductors in the manufacture of insulated wire and cable,although the present invention may be used in any fleld'ior which it isadapted by the nature of my improvements.

. The conductor to be coated may be composed of any metal or alloys usedto conduct electricity, for example, copper, steel, iron, bronze,nickel, or the like, and may comprise a single solid wire, or amultiplicity of wires forming a cable. The individual wires may have asurface coating of metal such as tin, lead-tin alloy, zinc, or oi otherknown or otherwise suitable materials, or the conductor may be providedwith a separator such as cotton, rayon, paper, cellophane, or anysimilar material, used as a. physical separator between the conductorand the rubber or rubber-like insulation.

Theinvention is equally available for applying dispersions, ashereinafter disclosed, to a fibrous strand, such as cotton, hemp, linenand the like,

whether in the form of yarn, thread, rope, cable,

or a braided, woven or crocheted structure, and

is also applicable to the various filaments used in the arts, such assilk and rayon.

Any suitable liquid, whether of natural or synthetic origin, may beapplied to the wire, and it is to be understood that the use of asolution or of a liquid dispersion as herein disclosed is merelyillustrative of a wide range of suitable coating materials.

When a liquid dispersion is used, it may consist of liquid latex of anydesired purity, consistency and concentration, preferably eitherprevulcanized in the liquid state, or containing our-- atives forsubsequent vulcanization; or use may be made of an artificially preparedaqueous dispersion of a compound of rubber orrubber-like materials;while another satisfactory material for the intended use comprises asolution of a compound of rubber or rubber-like materials in a solventother than water.

A conventional method for applying such dispersions or solutions hasbeen to run a wire through a bath of insulating material, either bypassing the wire around a pulley completely submerged in the bath, or byrunning the wire vertically through a stufiin-g box in the bottom of thebath.

Patent No. 1,870,990, wherein a wire is passed not.

Another method has been described in Letters vertically through atapered die on top of which is a small pool of the liquid dispersion. Athird method consists in spraying the liquid dispersion onto the wire.

In the employment of the foregoing methods, certain disadvantages andinconveniences have been encountered which render their commercial usenot altogether satisfactory, for various reasons, one reason being thatliquid dispersions of the nature mentioned are liable to become unthehearing, so that it has been standard prac tice to provide pivot pointbearings for this pulley, in order to reduce such friction to a minimum.This type of bearing, however, is not satisfactory when an appreciableload is applied to the pulley, because the pulley is apt to, be pulledentirely out of its supporting bracket, or the male portion of thebearing is caused to rotate on its side, rather than on its point, whichagain produces harmful friction.

Secondly, a dip tank that is large enough to hold a pulley and itssupporting 'brackeuholds a large volume of the liquid dispersion, and asthe amount of the liquid dispersion applied to the wire is relatively.very small compared. to the volume in the tank, there have arisendifiiculties in operation due to settling of compounding materials,resulting in a non-uniform product} while, due to normal surfaceevaporation, therehas often been formed a surface skin which becomesattached to the wire, producingan inferior prod- The large guantit'yofmateriatinvolved constitutes an added disadvantage.

Thirdly, if the liquid dispersion'is applied by passing the wire througha" stufilng roger a tapered die, enough friction may be created to formcoagulum -in or about the stufil'ngbo'x or die, and eventually all orapart of thiscoagulum may be transferred to the wire-thus turning outasubstandard product."

'Fourthly, spraying, as a means for coating'an article such as wire, isapt to be somewhat inexact and wasteful, du to the relatively small toafford satisfactory Under the above conditions, it is a primary objectof the present invention to provide for applying liquid dispersions andsimilar liquids to wire and the like by a method which shall eliminatethe foregoing and other disadvantages and incenveniences of operation,reduce the time and cost of production, and im-' prove the quality ofthe final product.

A cognate object of the invention is to provide improved apparatus bywhich'the above method can be carried into effect, as illustrated anddescribed in the accompanying drawings and specification and pointed outin the claim.

The invention consists in apparatus comprising means for feeding asubstantially continuous length of conductor upwardly under tension inan upright path, in combination with means for feeding a substantiallycontinuous stream of liquid in a curved path downwardly intointersection with said upright path, said means being constructed andarranged to operate at a speed ratio suitable to create, at theintersection of said paths, a puddle of the liquid maintainedautomatically by said feed ratio at a quantity adequate to formprogressively on the wire a coating of the desired thickness.

The invention consists also in other features of the invention which,together with ancillary objects thereof, will appear as the followingdescription of the embodiment of the invention selected for illustrationproceeds.

In the accompanying drawings:

Fig. 1 is a view in perspective of apparatus for the application of aliquid dispersion to wire in the construction of which apparatus thepresent invention has been embodied;

Fig.2 is .a similar view in perspective of the and which shall also formcoating rubber deposited from the liquid latex, this coating beingindicated at IS in Fig. 5.

The latex stream II, as it advances downwardly in the curved path I2,encounters at the application point M an upward wiping action or drag ofthe wire i5, so that the flow of the stream is retarded, and a puddle llof the liquid, such as a latex dispersion, is created, as illustrated inFig. 4 and in'Fig. 5, the sides of the puddle being confined, in theinstance illustrated, by the walls l9 and 20, of the grooved peripheryof thespplicator disc 22 which defines the curved path I! of the streamH, and which feeds the stream forwardly and downwardly'as the disc 22 isrotated. Such rotation is effected at a speed ratio relatively to thefeeding movement of the wire l5 suitable for maintaining the puddle I!at a quantity adequate to form on the wire 15 a unil8 of the desiredthickness. The thickness of the layer deposited depends essentially onthe viscosity, content of the liquid and on the rate at which the wirepasses through the puddle.

In pursuance of the invention, the stream II is preferably fed at a ratesuitable to supply the puddle I! with a quantity oiliquid latex somewhatin excess of that required to form the coatin'g progressively, and asthe disc 22 continues to rotate, the excess of latex dispersion iscontinuously drawn away from the path of the wire l5, as indicated at23, and is finally'fed upwardly, in its own curved path, as at 24, untilit becomes reincorporated with the main feed stream,

illustrative form of apparatus of Fig. 1, taken on from a differentdirection;

Fig. 3 is a fragmentary detail view on a still larger scale,illustrating in plan a singleapplicator unit of modified form shownseparately;

Fig. 4 is a fragmentary detail view in plan, 'on a still larger scale,of the applicator disc, shown separately from an applicator unit of anyof the a larger scale,

forms shown and illustrating the puddle of liquid I traversed by a wireto be coated;

Fig. 5 is a vertical section on the line 5-5 of Fig.4; and

Fig; 6 is a view of a part of the apparatus of Fig. 1 in frontelevation. v

Referring to the drawings, an apparatus for carrying into effect thenovel method of the present invention is illustrated which has beenfound production upon a com-. mercial scale, although it is shown merelyby way of illustration, preferred embodiment of the invention is notintended to exclude the use of other suitable apparatus designed to meetthe various requirements of particular applications of the invention.

The reference character It designates, in gen and its selection as anowas at 25, and it eventually reaches the puddle I! again, to beutilized in the coating process to the extent required.

Various means for supplying fresh increments of liquid latex to thestream ll may be utilized, and as a now-preferred construction for thispurpose, referring to Figs. 1 and 2, each applicator disc 22 is shown asmounted suitably over a reservoir 28 which contains a chamber l3 (seeFig. 3) for a supply of the liquid latex that is fed through a conduit21 into each reservoir, where its level is maintained relativelyconstant by any suitable means, such as a conventional form of externallevelling device (not shown). Adjusting means, as for example theslotted lugs and bolts 28, are provided, to permit the applicator units20 to be set to or from the wire II.

The transfer of the liquid latex from each reservoir 26 to the groovedperiphery of each applicator disc 22 may be accomplished by any shownherein as a feed disc I! by a shaft ll (see F18. 3) 3| upon the wall 32of the latex any deleterious effects of friction, thus eral, anapplicator unit constituting means for trated, constitutes the elongatedarticle to which 1 the liquid latex dispersion the purpose of forming anis to be applied, for insulating coating of avoiding any tendency tocoagulation from that source, and also eliminating the possibility ofhaving the bearing freeze, as no secretions of liquid latex will reachthe bearing. Each feed disc Ills partially submerged in the liquiddispersion contained in one of the units 28, and is driven in acounterclockwise direction by suitable means, such as the train of gearsas shown in Fig. 3, running to the shaft 3'. of disc I. from the drivingshaft 35.

In Fig. 6, the pulleys 38 of the battery. of applicator units 28 thereshown are illustrated as driven directly by belts 31 running to a commoncoimtershaft II. p 1

Each disc 2! lifts the dispersion upwardly and forwardly over its top,and transfers the same temperature and solids level of the liquid latex,

to its associated applicator disc 22 which is also driven in acounterclockwise direction by the drive shaft as, on which it is shownas mounted directly. Each feeding disc 28 and. its applicator disc 22are driven in a 1 to 1 ratio, but inasmuch as the feeding disc is ofgreater diameter, there is a difference in relative circumferentialspeed, and hence there is a wiping action at the region 28 where thev-shaped circumferential edge M of the feeding disc travels between thewalls i9, 20 defining the V-shaped groove M in the periphery of theapplicator disc 22. (See Fig. a V

This diiferential tends to flood the groove the applicator pulley at 25and the liquid dispersion thus fed to the applicator pulley is liftedand carried in the form of a substantially continuous stream i I (seeFig. 5) through the curved path i2 defined by the groove therein,downwardly and around to the point of application it, where thestream-path intersects the wirepath and the stream of liquid latexcontacts the wire i5, 9. self-maintaining puddle ll of the dispersionbeing created, which completely surrounds the wire, and from whichpuddle the wire emerges with a uniform coating it of the dispersion.

In the construction illustrated in Figs. 1 and 2, belts 31, like thoseabove described, run from the pulleys 38 to pulleys on short shafts II,and these in turn are driven by belts 20 running to the common drivingshaft 40.

The speed of each applicator pulley 22 is desirably approximately 1'75R. P. M. for coating a size 19 A. W. G. wire with a latex compound at42% total solids. This speed may be changed when diiferent size wiresare coated or when different concentrations or different types ofdispersions are used. It is to be noted that the showing of an invertedV-shaped periphery II on the feeding disc is not intended to exclude itsformation with a concave v-shaped periphery, and that a satisfactoryfinal result may be obtained by having only one grooved pulley acting asboth a feeding disc and applicator disc for each unit; also that theremay be two applicator discs having peripheral grooves cooperating faceto face; also that the discs may have variously shaped grooves, and thefaces of the grooves may be either smooth or serrated: and that the wire:7 may be fed in the same direction as the stream In the commercialoperation of the invention it is preferred to provide as alreadydescribed, a gang or battery of applicator units iii, sc operated thatthe wire it will be given a first coat it of the dispersion, inthe-manner already described, and will be then dried and returned toanother unit for a second application of dispersion which also will bedried, and so onwith alternate applications of liquid dispersion anddrying, as shown in Figs. 1, 2 and 6, until the coating i8 of dispersionhas the desired wall thickness.

The applicators may be driven by individual motors (not shown), in placeof the belt drive connections, between the drive pulleys It and ashafting'common to a battery of such applicators, asshown at All inFigs. 1 and 2 of the drawings. The several sections ll of the. conductorare shown in those figures and in Fig. 6, as running through heaters 42where the drying and vulcanization are performed, and the generalorganization of the apparatus appears clearly from Fig. 6. a

The sections 55 of the-wire are maintained under adequate tension asthey run over rigidly mounted ball-bearing pulleys 48, 44 at the top andbottom of the drying tower, thus improving the operation mechanicallyand causing the wire to run smoothly through each puddle, preferablywitheut making any physical contacts at the several applicator units, animportant feature that is novel in such apparatus and is made possibleonly by the novel provisions of the present method, as will beunderstood clearly from the foregoing disclosure. It is to beunderstood, however, that with coatings of some materials, the contactswith the periphery of a pulley will not interfere with the successfulpractice of the invention.

It will also be apparent that this apparatus for carrying the improvedmethod into eifect provides emcient means for avoiding the disadvantagesand inconveniences heretofore encountered in the application of liquiddispersions to wire and similar elongated articles, inasmuch as thecauses of coagulation by friction have been eliminated, the exposure oflarge bodies of latex dispersions has been avoided, and adequateprovision has been made for turning out a product of uniform excellence.

As various other modifications will occur to those skilled in the art,it is not intended to -limit the invention otherwise than as set forthin the appended claim.

Having thus described my invention, what 1 claim and desire to protectby Letters Patent is: Apparatus for applying an aqueous dispersion ofrubber or rubber-like material to a moving strand to coat the strandwithout subieoting the feeding a substantially continuous length of saidstrand upwardly tangentially to said groove through a portion of saidstream, to thereby create in said groove a self-renewing puddle of saiddispersion that is supported in a suspended condition by the upwardtravel of the strand.

FREDERICK B. BARTLETT.

